Crystal Structure of a Cobalt MOF Containing Cyclotriveratrylene and Its Application for Electrochemical Detection of Dopamine and Epinephrine.

Dopamine (DA) is a key neurotransmitter regulating nervous system function, while epinephrine (EP) is an important hormone reflecting pathological status. The accurate detection of these two molecules is of great clinical significance for the early diagnosis and therapeutic evaluation of related diseases. Metal-organic frameworks (MOFs) exhibit considerable potential in electrochemical sensing; however, pristine MOFs suffer from poor conductivity. In this work, the ligand H6L, a derivative of cyclotriveratrylene containing six carboxylic groups, was synthesized. A Co-L MOF was then constructed via a solvothermal method, and its crystal structure was determined and discussed. Then, Co-L was compounded with mesoporous carbon (MC) to give the composites for the modification of an electrode. Benefiting from the MC, the conductivity of the composite was significantly enhanced, and the electrochemical sensors containing the composite for the detection of DA and EP were constructed. Cyclic voltammetry (CV) was used to optimize of testing conditions, and differential pulse voltammetry (DPV) was used to detect the contents of analytes. For the detection of DA, the Co-L@MC(1:2)/GCE (ES-I) sensor displayed a linear range of 0.05-35 μM and a detection limit of 1.09 nM (GCE = glassy carbon electrode). For EP, the Co-L@MC(2:1)/GCE (ES-II) sensor possessed the linear range of 0.03-75 μM, and the detection limit was 1.55 nM. Meanwhile, both sensors exhibited good selectivity, repeatability, and stability, with all relative standard deviations (RSDs) below 5%.